I have a clear acrylic hard case for my E436F. I also like that it makes the player a little larger. The buttons are not covered and are easily accessible. The only thing I don't like is that I still have to be careful not to scratch the face, and that it is constantly getting dust under the case over the screen.

That is the one weakness of the case for my NWZ-E438F. The case for my NWZ-A818 completely covers my player (it has rubber buttons that cover the actual buttons on my player and allow me to use them as if they were the actual buttons) except for a small slot on the bottom for the cable connector and the headphone jack. and holes for the reset and hold buttons. Due to this, I rarely have a problem with dust getting into my player.

Still, I think the hard plastic case for the NWZ-E438F is worth purchasing. For me, the most important reason is to protect the most vulnerable part of the player: the screen. In fact, one of the prime considerations I have before purchasing an audio player is if there is a hard case for it (if the screen is prone to damage during normal use).